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High Availability & Hardware Failover
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OPNsense utilizes the Common Address Redundancy Protocol or CARP for hardware
failover. Two or more firewalls can be configured as a failover group. If one
interface fails  on the primary or the primary goes offline entirely, the
secondary becomes active.

Utilizing this powerful feature of OPNsense creates a fully redundant firewall
with automatic and seamless fail-over. While switching to the backup network
connections will stay active with minimal interruption for the users.

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Automatic failover
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If the primary firewall becomes unavailable, the secondary firewall will take
over without user intervention and minimal interruption.

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Synchronized state tables
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The firewall’s state table is replicated to all failover configured firewalls.
This means the existing connections will be maintained in case of a failure,
which is important to prevent network disruptions.

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Configuration synchronization
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OPNsense includes configuration synchronization capabilities. Configuration
changes made on the primary system are  automatically synchronized to the
secondary firewall.

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Configure HA CARP
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For detailed setup guide see: :doc:`/manual/how-tos/carp`